GMRS Repeater Basics: How to Extend GMRS Radio Range in the Backcountry
One of the major benefits of General Mobile Radio Service (GMRS) radios is their ability to use repeaters to extend their signal range. As more repeaters come online, the utility of GMRS radios for backcountry communications continues to grow. We use GMRS radios for communicating on overlanding trips and on off-road trails in areas where there is no mobile phone reception.
The tricky part for new GMRS users is figuring out how to connect with a repeater correctly, as it’s a bit more involved than with direct radio-to-radio (simplex) communications. In this article, I’ll give you a step-by-step guide to finding, connecting to, and transmitting via GMRS repeaters.
Here, I’ll assume you are familiar with basic GMRS use. If you are new to using GMRS radios for overlanding and off-road comms, a good place to start is our article on GMRS radio basics. It’s important to note that you need to purchase a license from the Federal Communications Commission (FCC) to operate a GMRS radio.
What is a GMRS Repeater?
GMRS (General Mobile Radio Service) repeaters are radio stations that receive and retransmit radio signals over a greater distance than is otherwise possible with a normal handheld or mobile radio.
They allow users to communicate over much larger areas, such as across a city, a valley, or over mountainous terrain. GMRS repeaters are typically located on high points, such as towers or mountaintops, and are usually operated by private individuals or organizations.
A handful of UHF channels and their corresponding frequencies are set aside for repeater use, which I’ll get into below. GMRS repeater stations have specialized software and hardware for relaying signals on these channels (aka, a duplexer) and often operate with larger antennas than typical GMRS radios. They are limited to transmitting at a maximum of 50 watts of power on repeater frequencies by the FCC.
Typically, GMRS repeaters work alone to relay incoming signals, but there are also networks of repeaters that can work together to daisy chain signals over even further distances.
How do GMRS Repeaters Work?
I’m not going to go into too much detail here, but I want to give you enough information so that you know the basics and don’t get confused by some of the quirks of radio lingo. GMRS repeaters are simpler to use than it will sound, but here we go.
Duplexing and Repeater Channels
When you are using your radio to communicate directly with another radio (simplex operation), you are sending and receiving channels on the same channel and frequency. In contrast, when you put your GMRS radio in repeater mode, it will operate on two different frequencies (duplex operation).
Your radio will send signals to the repeater on an output frequency/channel, a mode known as radio transmitter (TX). Your radio will receive signals from the repeater station on a different input frequency/channel, a function known as radio receiver (RX mode).
The eight output channels/frequencies for GMRS radios to send signals to repeaters are in the 467 MHz frequency band. The eight input channels/frequencies through which radios receive signals from repeaters are in the 462 MHz band. Each 462 band frequency will have a corresponding 467 band frequency that is exactly 5 MHz higher.
For example, the repeater station closest to my home in San Diego transmits at 462.675 MHz, so it would receive transmissions from my radio on 467.675 MHz, exactly 5 MHz higher.
The “462” channels are also used for normal radio-to-radio simplex communications, so you may pick up repeater transmissions when you are in simplex mode on those frequencies.
When a repeater is listed in a public directory, it will often (but not always) be identified by the frequency on which your radio will receive transmissions from the repeater (the 462 input frequency).
Discussions around duplex operations can get confusing. In my experience, it stems from the fact that depending on whether you are looking at it from the repeater’s perspective or your radio’s perspective, receive (input) and transmit (output) modes are the opposite.
When you send a signal to the repeater it’s an output signal (TX) for you but an input (RX) for the repeater. Likewise, when the repeater transmits a message it’s an output for the repeater (TX) but an input for the receiving radios (RX).
If it seems like different tables of repeater channels and frequencies conflict with one another, don’t worry. You aren’t going crazy. The seeming discrepancy is probably due to one table publishing info from the repeater’s point of view and another publishing it from the point of view of the person trying to connect with the repeater. Hope that makes sense.
Another point of confusion is that receiving “462” repeater channels (RX) are often listed with the channel number followed by an “R.” So Channel 15 becomes Channel 15R when you are operating in duplex. The transmission channels that your radio will use to send to a repeater are sometimes lumped in with the receiving channels on frequency/channel charts, and sometimes are listed as Channels 23-30, as they are the highest frequencies in the GMRS range. Confusing, huh?! I put together the chart above to help clarify the matter.
Repeater Codes (Tones)
The last thing I’ll cover in this section is “privacy codes”, which are essentially extra bits of information that can be tacked on to a GMRS signal. I put privacy codes in parentheses because people use a lot of different words to refer to this function: privacy tones, privacy lines, PL codes, etc.
These codes are a function of “squelch,” a function of radios that allows them to focus on certain frequencies or types of signal.
There are two types used by repeaters, one analog and one digital. Continuous Tone-Coded Squelch System (CTCSS) tones or “sub-audible tones” are low-frequency audio signals that are transmitted along with the voice signal. Most repeaters will require these tones to prevent interference from other users on the same frequency and to control access to the repeater.
When a user wants to access a GMRS repeater that requires a privacy tone, they must transmit the correct tone along with their voice transmission. The tone is removed from the signal before it is retransmitted by the repeater.
There are several different CTCSS tones that can be used, each with a different frequency. The specific tone used by a particular repeater will be determined by the owner or administrator of the repeater, and you must be aware of which tone to use in order to access the repeater. Some repeaters may use multiple tones, allowing access to different groups of users or for different purposes.
In addition to CTCSS tones, some GMRS repeaters may also use Digital Coded Squelch (DCS) tones. These are similar to CTCSS tones but are encoded digitally instead of as analog audio tone. DCS codes provide more precise control over access to the repeater, as the codes can be set to a specific pattern rather than a specific frequency.
For publicly available repeaters, the tones are typically available on online repeater directors. For restricted repeaters, you will need to ask the owner or club that manages repeaters for the tones. Some repeaters are strictly used for private purposes and the owners won’t share the access tones with you. See the section below for more info on finding repeaters.
Is My Radio GMRS Capable?
Not all GMRS radios can connect to repeaters, so it’s important to confirm that you are purchasing a model that does. Mobile units that install in vehicles tend to be repeater capable, but a number of handheld GMRS radio models aren’t.
To determine if your GMRS radio is repeater capable, check the specifications and manual of your device. The manufacturer’s website should also have information available. Amazon and other online e-commerce sites will often say if it’s repeater capable, but I’d double check on the manufacturer’s website.
If you already have a GMRS, you look for a setting or option in your radio’s menu that enables repeater use. Most GMRS radios that are repeater capable will already have channels set up for this feature. The setup process may vary from model to model, but once you have the basic principles down, using a GMRS radio repeater is not difficult. Also, check if the radio is both CTCSS and DCS capable.
How to Find GMRS Repeater Stations
There are a few ways to locate GMRS (General Mobile Radio Service) repeater stations:
There are several online directories that list GMRS repeater stations, such as myGMRS.com and RepeaterBook.com. These directories typically list the frequency, location, and owner information for each repeater.
Local Radio Clubs
You can also find information about local GMRS repeater stations by contacting local amateur radio clubs or GMRS user groups. They may be able to provide you with a list of active repeaters in your area and help you get in touch with the owners. Google the name of your town, city, or state and the words “GMRS” and see what you find.
You can also try scanning the GMRS frequencies with a GMRS radio to see if any repeater stations are in range. Reference the table above for the various frequencies and channels and watch for the scanning to find one of them.
As I mentioned above, not all repeater stations are accessible to the general public. Also, some repeater stations operated by private individuals or organizations may have specific usage rules or access codes.
You can see in this image below, from a listing on GMRS repeaters in my area from myGRMS.com, that two of the four repeaters near my house are private and you have to request access.
When to Use a GMRS Repeater
In any given area, there may only be one GMRS repeater (or none, sadly), so multiple parties may be trying to operate on the repeater channel.
Because of this, it’s important to only use a repeater when it is needed, to avoid crowding the repeater channel unnecessarily. Here are some reasons you might use a repeater:
Communicating in Obstructed Terrain
GMRS repeaters are a valuable tool for radio users who need to communicate in areas with obstructions, such as mountains or tall buildings. GMRS is a “line-of-sight” technology, so obstructions will interfere with radio signals and make it difficult or impossible to communicate directly, even with high-powered radios.
By using a GMRS repeater, however, you can essentially communicate around or over obstacles. This can be especially useful for outdoor activities such as off-roading, overlanding, hiking, camping, or backpacking in mountainous terrain, where clear communication can be a matter of safety and success.
If you have gotten separated from another vehicle in your party, for instance, and they are over a mountain ridge that happens to have a GMRS repeater on top, you may be able to connect with each other.
One thing to keep in mind is that a repeaters signal range is not the same as your radio’s signal range. Let’s say a repeater has a 60-mile range, and at your current position, you fall well within that range. But that doesn’t mean that your radio can send a signal to the repeater.
If you are 10 miles away from the repeater, using a handheld GMRS, you may be able to hear the transmissions from the repeater but chances are your signal won’t reach the repeater. I can pick up incoming signals from several repeaters, but can’t reach any of them with my handheld radio transmissions.
Communicating Beyond Your Radio Range
In simplex mode, a GMRS radio will typically have a line-of-sight signal range of 2 to 30 miles, depending on the frequency used and the radio’s power and antenna. A single GMRS repeater could relay that transmission another 30 miles or much further if it has a large antenna, greatly extending the range.
As an example, here in Southern California, where I live, I’m often in areas where there is spotty or no mobile phone reception. I’m in the open desert so a GMRS signal could travel quite a way unobstructed but my radio may not have the signal power to reach my friend who is 30 or 40 miles away.
In this case, a repeater could extend our communications range quite a distance – assuming we both know the channel to connect through in advance. Advanced planning is key in such situations.
In an emergency situation, a GMRS repeater can be used to call for help. The potential for extended range and transmission in obstructed terrain, outlined above, means a repeater will broadcast further than your radio working in simplex. Also, repeater frequencies may have more users monitoring them.
When I go into the backcountry, I bring a satellite communications device also, as certain models (eg SPOT, inReach), can directly alert authorities that you need assistance in an emergency. I personally wouldn’t rely on two-way radios alone for requesting assistance.
How Do I Connect With a GMRS Repeater Station?
Now that we’ve covered the basics of GMRS repeaters, I’ll walk you through the steps to connect your GMRS radio to a repeater station. Before you begin transmitting on a GMRS repeater, please read the section below on proper etiquette.
Verify the Frequency and Tones
Before connecting your GMRS radio to a GMRS repeater station, verify the frequency of the repeater station you want to connect to. Make sure the repeater is publically accessible or that you have permission from the owner (if needed). Also, note any privacy tones you’ll need to access the repeater.
Program Your Radio Frequency
Program the repeater frequency into your radio – this will be the “462” frequency that your radio will receive signals on. Follow the instructions in your radio’s manual to program the correct frequency.
Adjust the Tone
If the repeater station requires a tone to access it, you’ll need to program that tone into your radio. This is usually done using the same programming interface you used to program the frequency. Websites that list repeaters, such as myGMRS.com, often provide the tones needed to connect with repeaters. However, they won’t list them for private repeaters.
Make a Test Call
Once your radio is programmed with the correct frequency and tone, you may hear people talking on the channel. To confirm you are connected, you can make a test call to ensure that you have access the repeater station. If everything is working correctly, you should be able to hear your own transmission repeated back to you through the repeater station.
Start Using the Repeater
If your test call was successful, you’re now ready to start using the repeater station to extend the range of your GMRS radio. Just make sure to follow the rules and regulations for GMRS radios when you transmit. Below are some guidelines on repeater etiquette.
GMRS Repeater Etiquette
When using a GMRS repeater, it’s important to follow basic etiquette guidelines to ensure that the repeater is used in an efficient and respectful manner.
While you may share a frequency when communicating directly with another radio, on a GMRS repeater you are more likely to be sharing the channel with other users. This is because there may be only one repeater in the area, which makes etiquette even more important.
By following these guidelines, GMRS repeater users can ensure that the repeater is used in a safe, efficient, and respectful manner and that it remains a valuable resource for emergency communications and personal use.
- Identify yourself
When using a GMRS repeater, always identify yourself by stating your call sign every 15 minutes during longer transmissions and at the end of each transmission (this is required by the FCC). It helps other users to know who is speaking and to keep track of the conversation.
- Wait for the repeater to clear
Before transmitting, wait for the repeater to clear and listen for any other ongoing conversations. Interrupting an ongoing transmission is not only disrespectful but also hinders communication and can cause confusion.
- Keep transmissions short and to the point
When using a GMRS repeater, keep your transmissions short and to the point. Long, drawn-out transmissions can cause other users to lose interest and block the frequency for more important communications.
- Avoid foul language
When using a GMRS repeater, avoid using foul language or making inappropriate comments. This helps to maintain the professional atmosphere of the repeater and makes it a welcoming environment for all users.
- Follow the rules
GMRS repeaters are regulated by the FCC and have specific rules and guidelines that must be followed. Be sure to familiarize yourself with these rules and follow them to avoid any penalties or fines.
That’s the gist of it. I know it’s a lot of information, but this should set you up for the basics of using a GMRS repeater. I recommend just listening in on a channel for a while so that you can get a sense of the protocols and etiquette for how people communicate over repeaters.
But don’t be afraid of using one. As long as you aren’t doing something egregious – like spouting obnoxious political or sales information or being rude or obscene, you should be fine.
As I mentioned before, if you are just getting started with two-way radio communication, I recommend reading our broadest intro guide to overlanding communications. If you have focused on getting a GMRS radio – which I recommend – our basic guide to GMRS radios will help get you up and running.